This invention relates to elements for use in inductive couplers for down-hole components, more specifically this invention relates to elements comprising segments of magnetically conductive material.
U.S. Pat. No. 6,670,880, which is herein incorporated by reference, discloses a downhole transmission system through a string of downhole components. A first transmission element is located in one end of each downhole component, which element includes a first magnetically conducting, electrically-insulating trough, and a first electrically conductive coil lying there in. A second data transmission element is located in the other end, with a similar arrangement comprising a second magnetically conducting, electrically-insulating trough and a second electrically conductive coil. The transmission system further comprises an electrical conductor in electrical communication with and running between each first and second coil in the downhole component. The string of downhole components is cooperatively arranged such that the elements are in magnetic communication with each other to thereby transmit signals through induction.
U.S. Pat. No. 6,670,880 discloses that the magnetically conductive troughs are preferably easily magnetized and demagnetized. Examples of magnetically conductive materials were given including soft iron, ferrite, nickel iron alloys, silicon iron alloys, cobalt iron alloys and mu-metals. One example of a nickel/iron alloy has a trade name of Permalloy, which is a compound that comprises about 20% iron and 80% nickel. A preferred magnetically conductive material is ferrite.
Rectangular segments are used as a substitute for a solid ring in the '880 patent. Naturally, a circular trough comprising rectangular segments creates gaps between its segments. Rectangles by definition are not curved and do not conform to the curve created by the circumferences of the circular trough. Thus, interruptions including generally triangular or trapezoidal shaped gaps in the trough result from using the rectangular segments. Because the gaps in the magnetically conducting circular trough do not contribute to magnifying the magnetic field, it is now believed that these gaps may adversely affect the magnetic field generated by the magnetically conductive, electrically insulating trough.